Manufacture of artifcial fibers



Patented Sept. 13, 1932 UNITED STATES PATENT OFFICE,

nnnmrcn FINK AND raur. nssnnmm, or ranmmrz, wns-rnnvnnmmn, GERMANY,

ASSIGNORS TO I. G. FARBENINDUSTBIE AKTIENGESELIiSCHAFT, F FRANKFORT- ON-THE-MAIN, GERMANY, A GORPORA TION OF G 'ERMAIN'Y mnurac'runn or anrmcmr. nimus Nobrawing. Application filed March-6, 1929, Serial 1T0. 844,910, and in Germany March 14, 1928,

dry tensile strength. Additional objects of 0 our invention are the new threads.

Further objects of our invention will be seen from the detailed specification following hereafter.

Our invention is basedon the observations that. viscose, when brought into the form of threads, bands, etc., is coagulated by an acid ester, made by partly esterifying a polybasic mineral acid with an alcohol, the alkyl groups of which may be substituted. The products thus obtainable have excellent properties especially a high wet and dry tensile strength. As a precipitating liuqid we may use, for instance, a mono ester of sulfuric acid or a mono or di-e'ster of phos horic acid. These acids may be partly esterified with a monovalent aliphatic alcohol, such as methyl alcohol, ethyl alcohol, propyl alcohol or with an araliphatic alcohol, such as benzyl alcohol I or with a polyvalent alcohol, such as glycol, 30

glycerin, trimethylene glycol or with a substituted alcohol, suchas glycolic acid. Other substituted alcohols forming acid esters with polybasic mineral acids may be used in the same manner.. v I

The action of our new precipitating liquids may be explained as follows:

A dibasic acid, for instance, sulfuric acid, becomes monobasic by esterificationof one of its hydroxyl groups with an alcohol and thus forms a precipitating agent which shows, even in undiluted form, only half the acidity of sulfuric acid. Therefore, the partly esterified compound can be applied in a concentration much higher than the mineral acid itself without damaging the regen erated cellulose. fiber. I

This may be proved, for instance, by the following test When treating a finished artificial fiber having a titer of 1 denier with sulfuric acid of about 75% strength, the fiber is damaged in to seconds. Even by a sulfuric acid of strength the filament is damaged in about 2 minutes. In contradistinction thereto, when using monomethyl sulfuric acid (prepared in the usual manner from two parts of concentrated sulfuric acid and one] part of methyl alcohol), the fiber remains unaltered for 3-4 hours.

It is not necessary to use the partly esterified acid in a chemically pure form when carrying out our process on alarge scale. A suitable precipitating bath is obtainable, for instance, by mixing equimolecular parts of the alcohol with the concentrated polybasic mineral acid or with-its anhydride or with the corresponding acid chloride, care being taken that the temperature of the mixture is regulated in such a manner that the best possible yield of the ester is obtained.

In our precipitating bath an excess of the acid or the alcohol may be employed. As a rule, when using an excess of the acid, a more rapidly acting precipitating bath is formed,

while an excess of alcohol diminishes the coadded to the precipitating bath. In any case, however, the precipitating liquid shall contain at least 30% of the acid esters in question. Inorganic salts which are soluble in our precipitating bath may be added, for instance, sodium sulfate, sodium bisulfate, ammonium sulfate, zine sulfate, sodium bisulfite.

Our new precipitating baths are especially useful in the manufacture of fine artificial threads of 31 deniers and even of finer fibers from an unmatured viscose prepared from unmatured alkali cellulose, for instance, according to U. S. Patent 1,428,246. Good results may even be obtained by subjecting the alkali cellulose to a previous ripening process whereas the viscose is not allowed to mature. When using our new precipitating bath without special stretching apparatus, an artificial silk is obtainable which has a high luster.

8 a. very soft feel and a dry tensile strength of about 2 grams or more per denier and a wet tensile strength of about 1.3 grams per denier.

sired, the same or similar products may be already added to the viscose itself.

The threads may be stretched in any known manner while in the precipitating bath or after they have been removed from it, that is, between the spinning bath and the collecting device, such as a bobbin or centrifuge. Th1s may be done, for example, by choosing a longer way between the bath and the collecting device or by leading the threads over rods or rolls arranged in such a manner in the bath or between the bath and the collecting device that the threads form one or more axigles on their way, or by using a suitable thread guide or by leading them into a second bath in which they may be simultaneously freed from the adhering coagulating liquid. The length of the thread immersed in the spinning bath may be varied Within Wide limits, for example, from 5 to 100 centimeters, said limits depending generally upon the temperature and nature of the coagulatin bath and of the nature of the viscose solution applied. We prefer to keep the spinning bath at ordinary temperature, it may, however, likewise be varied within wide limits, and good results are-obtainable at temperatures of about 0 to 40 C. The drawing speed of spinning may be varied up to 7 5 meters per minute, depending partly upon the temperature and nature of the bath, partly upon the length of immersion and the thickness of the thread, partly upon the viscosity of the spinning solution and finally upon the quantity of viscose solution pressed into the precipitating bath.

The following examples serve to illustrate the invention without limiting it thereto: 'E'mampZe 1.1'00 kilograms of methyl alcohol of 99% strength are mixed with 200 kilograms of sulfuric acid of 96% strength,

the temperature of the mixture being kept for 2 hours at 4050 C. By this time the acidity of the mixture has become stable as proved by titration. From the difference between the total amountof 64-66% by weight of sulture of about 41% of acid calculated as H SO it is found that the ath contains about 18% by weight of sulfuric acid monohydrate and about 52-53% of mono-methylester of sulfuric acid, the remainder being unaltered methyl alcohol and water formed by the esterification.

A viscose solution containing 56% of cellulose and 57% of NaOH prepared from an entirely unmatured alkali cellulose, for instance, according to U. S. Patent 1,428,246 is pressed immediately after dissolving and filtering into a precipitating bath prepared as described above. Through a spinning openin of about 0.1 millimeter diameter at a drawing speed of about 30 meters per minute the viscose pump delivers such a quantity of viscose that a thread of 1 denier is formed. The temperature of thez-bath is kept at about 1520 (1., the length of immersion being about 50-100 centimeters. After having passed the precipitating bath, the thread is guided over rods or rolls into a second bath where it is washed with water and then to a collecting device, for instance, to a bobbin, irrigated with freshwater. The well washed threads are freed from sulfur, bleached and finished in the usual manner known in the viscose art.

Example 2.The same viscose solution as mentioned in Example 1 is spun under the same conditions into thesame bath but at a bath temperature of 35 C. and a length of immersion of 15 centimeters.

Example 3.The same viscose as described uric acid and the total aciditi of the mix- .in Example 1 is spun with a length of immersion of 30 centimeters into a coagulating bath, made by mixing of 100 kilograms of ethyl alcohol of 95% strengthvwith 200 kilograms of concentrated sulfuric acid-of 96% strength and heatin until the esterification has been finished. e recipitating bath contains about 49% of et yl sulfuric acid and 27% of sulfuric acid; By glass rods of suitable thickness there are im arted so much angles to the filament that spinning isstill possible. All the other conditions are the same as described in Example 1.

Ewmple 4.The same viscose as described in Example 1, is spun under the same conditions as. in Example 3-'but with a length of immersion of 40 centimeters into a precipitatingbath,'ma-de of 200 kilograms of technical butyl alcohol and 400 kilograms of concentrated sulfuric acid. In order to diminish the high viscosity of the finished reaction mixture 100 kilograms of water are added. The bath contains about 53% of butyl sulfuric acid and 23% of sulfuric acid.

Ewample 5.The same viscose as described in Example 1, is spun with a length of immersion of 15 centimeters into a precipitating bath kept at a temperature of 1520 C. which is made in the following way follows a content 52.5% of methyl sulfuric acid and 26% of sulfuric acid in the bath.

The other conditions are the same as in Example 1.

Ewample 6.-The same viscose as described in Example 1, is pressed into abath made by introducing. 7 0 kilograms of phosphoric acid anhydride into 50 kilograms of methyl alco-' hol. The mixture, after filtering from the undissolved, titrated with baryta water, contains 46.3% of monomethyl phosphoric acid 34.9% of dimethyl phosphoric acid and 3.2%,-

of phosphoric acid. Before .using it of water is added to the bath. The length of immersion amount..- to 20 centimeters, the

bath temperature is 15 C. .The drawing speed amounts to about thirty five meters per minute. The viscose pump delivers such a quantity of viscosethat a thread of 1 denier is formed.

Eaample 7.The same viscose and acid as described in Example 5 are used. The viscose pump however is caused to deliver the double quantity of viscose so that a thread of 2 denier is formed. The diameter of the spinning openings amounts to 0.08 millimeters.

Example 8.The same viscose and acid as described in Example 5 are used. Butthe viscose pump is caused to deliver such a quantity of viscose, that a thread of 0.5 denier is formed. The diameter of the spinning openings amounts to 0.08 millimeters.

-Emample 9.The same viscose as described inExample 1, is spun through a nozzle having 600 spinning openings of 0.1 millimeter diameter at a drawing speed of about sixty meters per minute into'a precipitating bath of a length of 60 centimeters of the same composition as described in Example 1, at a temperature of 25 C. while stretching over sev-' eral glass rods upon a reel which is irrigated with water. The hank is cut oil, washed, finished and prepared for staple fibers.

E azample 10.-An alkali cellulose, made by immersing one part of sulfite cellulose in 15. parts of caustic soda'solution containing 18% I of its weight of NaOH at the temperature of 13 C. for two hours after having been pressed to' the triple weight of cellulose and disintegrated, is matured four days at a temperature of 18 CJ The matured alkali cellulose is well xanthogenized with a quantity of carbon .disulfideamounting to 40-50% of the weight of cellulose, the formed xanthogenate beingthereafter dissolved at a temperature below +10 C. to a viscose containing 78% of cellulose and 67% of NaOH. The finished viscose, which does notshow any ammonium chloride titer'according to Hottenroth is spun immediatelyzaccording to the arrangementand with the acid described in Example 1. The quantity ofviscose to be delivered from the pump and the speed of drawing must'be adapted in a manner as to form a thread of 1 denier.

lose as described in Example 10, a viscose is made containing 78% of NaOH and 10% of cellulose with the same viscosity. It is spun as described in Example 10 into the same we cipitating bath, the quantity of viscose to be delivered from the pump bein 3.2 ccm per minute. A drawing speed of about 30 centimeters per minute is maintained so that, when applying a spinning nozzle of 120 spinning openings with a diameter of 0.08 millimeters,

a thread with the titer of 1 denier is obtained.

The threads thu'sobtainable have a dry tensile strength of3 grams and more per denier and in' the wet state 1.8 to 3 grams per denier. Dry and wet stretching amounts to 58%. They have an'excellent soft feel and luster; the luster is a little duller than that of the usualartificial silks; their capacity of beingdyed equals to that of other viscose silk prepared in the usual manner. Owing to thelr high tensile strength, they are well fit for being worked on textile machines.

In the followin claims the expression an acid ester of poly asic mine'raLacid with an aliphatic alcohol is intended to include all products which are obtainable by partly es- Emample lie-From the same alkali cellu-,

so i

terifyinga polybasic mineral acid with an aliphatic, alcohol which ma be substituted :When using the express on completely unmatured viscose, we mean unmatured viscose prepared from an unmatured alkali cellulose, forinstance, in accordance with'jU. S. Patent 1,428,246.

Havingnow particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:

1. The process for manufacturing artificial fibers from viscose; which comprises pressing. a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of-an acid ester of a poly-v basic mineral acid with an aliphatic alcohol.

2. The process for manufacturing artificial fibers from viscose, which comprises pressing pressing a viscose solution through a spinfuric acid ning nozzle into a precipitating bath taining at least of an acid ester of furic acid with a n aliphatic alcohol.

5. The process for manufacturing artificial 'fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into aprecipitating bath con taining at least 30% of an acid ester of sulwith a monovalent aliphatic consulcial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath obtained by esterifying about molecular proportions of sulfuric acid and of methyl alcohol. v

9. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into'a precipitating bath containing at least 30% of an acid ester of a polybasic mineral acid withan aliphatic alcohol and stretching the freshly coagulated threads.

10. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of an aci d ester of a polybasic mineral acid witha monovalent aliphatic alcohol and stretching the freshly coagulated threads.

11. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of a methyl ester of a polybasic mineral acid, and stretching thefreshly coagulated threads.

12. The process for manufacturing artificial fibers from viscose, which comprisespresslng a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of an acid ester of sulfuric acid with an aliphatic alcohol, and stretching the freshly coagulated threads. 4

13. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing 08 at least 30% of an acid ester of sulfuric acid with a monovalent aliphatic alcohol, and stretching the freshly coagulated threads.

14. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of sulfuric acid monomethyl alcohol, and stretching the freshly coagulated threads.

16. The process for manufacturing arti' ficial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath obtained by esterifying about molecular pro ortions of sulfuric acid and of metliyl alco 01, and stretching the freshly coagulated threads.

17. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of an acid ester of a polybasic mineral acid with-an aliphatic alcohol and immediately subjecting the freshly formed threads to a washing operation.

18. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzleinto a precipitating bath containing at least 30% of an acid ester of a polybasic ,mineral acid with a monovalent aliphatic alcohol and immediately subjecting the freshly formed threads to a washing operation.

19. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of a methyl ester of a polybasic mineral acid and immediately subjecting the freshly formed threads to a washmg operation.

20. The process ficial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of an acid ester of sulfuric acid with an aliphatic alcohol and immediately subjecting the freshly formed threads to a washing operation.

21. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of an acid ester of sulfuric acid with a monovalent aliphatic alcohol and immediately subjecting the freshly formed threads to a washing operation.

22. The process for manufacturing artia viscose solution through a spinning for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath containing at least 30% of sulfuric acid monomethyl ester and immediately subjecting the freshly formed threads to a washing operation.

23. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath obtained by esterifying about molecular proportions of sulfuric acid and of a monovalent alcohol and immediately subjecting the freshly formed threads to a washing operation.

24. The process for manufacturing artificial fibers from viscose, which comprises pressing a viscose solution through a spinning nozzle into a precipitating bath obtained by esterifying about molecular proportions of sulfuric acid and of methyl alcohol and immediately subjecting the freshly formed threads to a washing operation and stretching the coagulated threads.

25. A precipitating bath for manufacturing artificial fibers from viscose containing at least 30% of an acid ester ofsulfuric acid with a monovalent aliphatic alcohol.

26. A precipitating bath for manufacturing artificial fibers from viscose containing at least 30% of an acid ester of sulfuric acid with a monovalent aliphatic alcohol ,to-which ester up to 30 per cent. of water is added.

27. A precipitating bath for manufacturing artificial fibers from viscose containing at least 30% of sulfuric acid monomethyl ester. T

28. The process for manufacturing artificial fibers from viscose, which comprises pressing an unmatured viscose into a precipitating bathcontaining at least 30% of an acid ester of sulfuric acid witha monovalent aliphatic alcohol.

29. The process for manufacturing artificial fibers from viscose, which comprises pressing an unmatured viscose into a precipi-. tating bath containing at least 30% of sulfuric acid monomethyl ester.

30. The process for manufacturing artificial fibers from viscose, which comprises pressing a completely unmatured viscose into a precipitating bath containing at least 30% of an acid ester of sulfuric acid with a-monovalent aliphatic alcohol.

31. The process for manufacturing artificial fibers from viscose, which comprises pressing a completely unmatured viscose into a precipitating bath containing at least 30% of sulfuric acid monomethyl ester.

32. Artificial fibers consisting of regenerated cellulose having a dry tensile strength of more than 2 grams per denier and a wet tensile strength of more than 1.25 grams per denier, obtained by the process as claimed in claim 1.

33. Artificial fibers consisting of regenerated cellulose having a dry tensile strength of more than3 grams per denier and a wet tensile strength of 2 grams and more per denier, obtained by the process as claimed in tures.

. HEINRICH FINK.

PAUL ESSELMANN. 

